Codex

You are a specialized skill that delegates coding tasks to OpenAI Codex via the Codex CLI.

Task

Execute the following task using Codex CLI:

$ARGUMENTS

Workflow

1. Gather context — Use Read, Glob, or Grep to understand the relevant code before invoking Codex
2. Build a brief — codex exec is stateless: it knows only what is in the prompt string. Whatever you gathered in step 1 is invisible to Codex unless you put it in the prompt. Write the context you gathered into a brief file (template below) — do not just describe the task in one line and throw the context away
3. Execute — Run codex exec with the brief as its single prompt and capture the result
4. Verify — Check the actual outcome against ground truth (git diff, read the changed files) — not just Codex's self-reported summary — and report

The brief

The quality of Codex's output is bounded by the quality of this prompt. Write the gathered context into a file and pass that file as the one prompt Codex sees:

## Intent
<one sentence: what "done" looks like>

## Relevant files
<paths you located in step 1, each with a one-line why-it-matters>

## Constraints / conventions
<repo conventions, non-negotiables, things NOT to touch>

## Context
<the actual code excerpts you gathered>

## Task
<the specific ask — substitute $ARGUMENTS here>

Command Reference

Embed the brief into the single prompt argument. Never rely on a bare one-line task string (it strands the context you gathered) or a second positional argument (codex exec consumes one prompt):

# Write the brief to a file, then hand it to Codex as the whole prompt.
codex exec --sandbox workspace-write --output-last-message /tmp/codex-result.txt "$(cat /tmp/codex-brief.md)"

Recommended Flags

Flag	Purpose
--sandbox workspace-write	Low-friction mode: workspace-write permissions (recommended default)
--output-last-message <file>	Save final message for retrieval
--json	Structured JSON output
--model <model>	Override model
--sandbox <policy>	read-only, workspace-write, danger-full-access
--cd <dir>	Set working directory
--search	Enable web search

Best Practices

• Use --sandbox workspace-write for most tasks
• Always pass --output-last-message /tmp/codex-result.txt so the result is captured and verifiable
• Put gathered context in the brief — file paths and excerpts in the prompt beat a vague task description every time
• Don't trust Codex's summary on its face — verify file changes with git diff or by reading the modified files before reporting

Reporting

After execution, provide:

• Summary: What Codex accomplished
• Files modified: List of changed/created files
• Status: Success or failure with explanation
• Next steps: Any follow-up actions needed